There are already known various constructions of accelerometers, among them such utilizing a very thin doped silica plate resiliently suspended between two capacitor plates as a proof mass that is displaced by acceleration forces out of its rest or null position, with attendant changes in the capacitances and electrostatic fields existing between the proof mass and the capacitor plates that are charged to different electrical potentials. It is also already known to determine the extent and direction of the displacement of the proof mass out of its rest position from the electric current which flows into or out of the proof mass as a result of electric potential variations occurring in the proof mass when it is displaced out of its rest position due to the aforementioned changes. However, experience with accelerometers of this type has shown that they provide very unreliable measurement results, particularly since the value of the aforementioned electric current is a complex, and by and large unpredictable function not only because the potential change in the proof mass in a non-linear function of the displacement and is also dependent on the potential difference between the capacitor plates which it may be very difficult or impossible to maintain constant at all times or over an extended period of time, but also because the displacement itself is a non-linear function of the acceleration forces acting on the proof mass owing to, among others, non-linear response of the resilient means, such as flexible hinges, which mount the proof mass in its position between the capacitor plates, the effects of aging on the mechanical properties of the hinges, temperature related changes in mechanical properties and dimensions, and the like.
Accordingly, it is a general object of the present invention to avoid the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide an accelerometer arrangement which does not possess the disadvantages of the known arrangements of this kind.
Still another object of the present invention is so to develop the accelerometer arrangement of the type here under consideration as to provide reliable measurement results with a very high degree of precision.
It is yet another object of the present invention to devise an electrical driving circuit for use in an accelerometer arrangement of the above type, which circuit renders it possible to obtain a highly reliable and precise indication of the acceleration forces acting on the proof mass.
A concomitant object of the present invention is to design the driving circuit and accelerometer arrangement of the above type in such a manner as to be relatively simple in construction, inexpensive to manufacture, easy to use, and yet reliable in operation.